CT appearance of pulmonary carcinomas after stereotactic radiation therapy

Analysis of radiological lung changes after stereotactic body radiation therapy

PURPOSE

Stereotactic body radiation therapy is indicated in cases of early inoperable lung cancer and surgical rejection, and it is also an option for oligometastatic, recurrent, and/or relapsing tumours. The aim of this study was to analyse the incidence of different patterns of radiological changes on CT scans, correlate their occurrence with risk factors, and analyse the usefulness of imaging information to predict treatment outcome in terms of local progression-free survival.

MATERIALS AND METHODS

A retrospective review was carried out on the data from 104 patients who received lung stereotactic body radiation therapy between 2014 and 2022. A first check-up visit was carried out a month after treatment. Visits were then performed every 3 to 4months during the first year, with imaging tests (CT or PET), and every 4 to 6months after the first year. Acute radiological changes were defined as those occurring in the first 6months and chronic radiological changes as those occurring starting from 6months onwards following treatment.

RESULTS

Acute radiological changes were detected in 44.44 % of the patients, with up to 86 % of them appearing chronically. The modified conventional fibrosis pattern was the most prevalent. Having received lung thoracic radiotherapy and irradiation of tumours located in peripheral regions significantly increases the likelihood of chronic radiological changes appearing. Fifteen patients underwent further tests such as a PET scan for suspected local progression after the appearance of chronic changes, of which 11 were positive. No association was identified between the occurrence of either acute or chronic radiological changes with worsened survival or a higher percentage of local progression.

CONCLUSIONS

Proper knowledge of the different patterns of radiological changes secondary to lung stereotactic body radiation therapy and their dynamics over time is necessary to discern between a benign pathology and progression.

Radiographic findings after stereotactic body radiation therapy for stage I non-small cell lung carcinomas: retrospective analysis of 90 patients

Aim:

Stereotactic body radiation therapy for lung tumours can expose patients to radiation pneumonitis (RP) (<6 months after irradiation) and lung fibrosis (beyond 6 months). The aim of this study was to describe post-irradiation radiographics appearances.

Materials and methods:

This retrospective study of 90 patients with a stage I non-small cell lung carcinoma reports a detailed description of the computed tomography (CT) or positron emission tomography/CT changes that can be observed after treatment, according to modified Kimura score for RP and Koenig’s classification for fibrosis. This evaluation was realised at 1 month and then every 3–4 months, with a median follow-up of 35 months.

Results:

The most common radiological RP pattern was diffuse consolidation. It appears in a mean time of 4 months and reaches its maximum at 9 months after radiotherapy. Seventy-three per cent of the RP evolved to fibrosis. Most of these findings were encompassed in the 35 Gy isodose.

Findings:

Radiological parenchymal changes are frequent in the treatment region, which renders the tumour response monitoring by tumour size, particularly by response evaluation criteria in solid tumours, unsuitable.

Surveillance After Treatment of Non-Small-Cell Lung Cancer: A Call for Multidisciplinary Standardization

OBJECTIVE

Though interest in expansion of the use of less-invasive therapies among operable non-small-cell lung cancer (NSCLC) patients is growing, it is not clear that post-treatment surveillance has been comparable between treatment modalities. We sought to characterize institutional surveillance patterns after NSCLC therapy with stereotactic body radiation therapy (SBRT) and lobectomy.

METHODS

NSCLC patients treated with lobectomy or SBRT (2005 to 2016) at a single institution were identified. Natural language processing searched data fields within axial surveillance imaging reports for findings suggestive of recurrence. Duration and patterns of institutional surveillance were compared between the 2 groups.

RESULTS

Three thousand forty-two patients (73.5% lobectomy, 26.5% SBRT) met inclusion criteria. Patients had a longer median duration of surveillance after lobectomy (28.0 months vs SBRT 12.3 months, P < 0.001) and were more likely to undergo histopathological evaluation of clinically suspected relapse (206/274 [75.2%] vs SBRT 54/113 [47.8%], P < 0.001). Patients with clinical suspicion of recurrence had longer durations of institutional surveillance than those who did not among both cohorts (lobectomy 44.4 months vs 25.9, P < 0.001; SBRT 27.9 vs 10.3, P < 0.001). Landmark analyses at 1 and 3 years after therapy identified associations between receipt of lobectomy and ongoing surveillance at each time point (1 year odds ratio [OR] 2.10, P < 0.001; 3 years OR 1.71, P < 0.001) among all patients and those with documented stage I disease.

CONCLUSIONS

We identified potential heterogeneity in institutional surveillance patterns after treatment of NSCLC with 2 therapeutic modalities. As less-invasive treatment options for operable patients expand, it will be critical to implement rigorous surveillance paradigms across all modalities.

Lung Cancer Recurrence: 18F-FDG PET/CT in Clinical Practice

OBJECTIVE

The purpose of this article is to summarize the clinical utility of ¹⁸F-FDG PET/CT in the evaluation of lung cancer recurrence with an emphasis on typical anatomic and metabolic patterns of recurrence, expected posttherapeutic changes, and common pitfalls of FDG PET/CT. FDG PET/CT is useful in assessing therapeutic response and in determining the extent of recurrent disease and provides a guide for targeted biopsy.

CONCLUSION

FDG PET/CT plays a crucial role in the evaluation of therapeutic response in lung cancer and guides management.

[Radiation-induced lung toxicity predictors after stereotactic radiation therapy for non-small cell lung carcinoma stage I]

In case of refusal or contraindication for surgical management of a stage I non-small cell lung carcinoma, the validated alternative therapy is stereotactic irradiation. This technique reaches an equivalent tumour control rate than surgery and significantly higher than conventional radiotherapy. One of the dreaded complications is radiation induced lung toxicity (radiation pneumonitis and lung fibrosis), especially when it is symptomatic, occurring in about 10 % of cases. This article is a literature review of this complication's predictive factors.

Long term radiological features of radiation-induced lung damage

PURPOSE

To describe the radiological findings of radiation-induced lung damage (RILD) present on CT imaging of lung cancer patients 12 months after radical chemoradiation.

MATERIAL AND METHODS

Baseline and 12-month CT scans of 33 patients were reviewed from a phase I/II clinical trial of isotoxic chemoradiation (IDEAL CRT). CT findings were scored in three categories derived from eleven sub-categories: (1) parenchymal change, defined as the presence of consolidation, ground-glass opacities (GGOs), traction bronchiectasis and/or reticulation; (2) lung volume reduction, identified through reduction in lung height and/or distortions in fissures, diaphragm, anterior junction line and major airways anatomy, and (3) pleural changes, either thickening and/or effusion.

RESULTS

Six patients were excluded from the analysis due to anatomical changes caused by partial lung collapse and abscess. All remaining 27 patients had radiological evidence of lung damage. The three categories, parenchymal change, shrinkage and pleural change were present in 100%, 96% and 82% respectively. All patients had at least two categories of change present and 72% all three. GGOs, reticulation and traction bronchiectasis were present in 44%, 52% and 37% of patients.

CONCLUSIONS

Parenchymal change, lung shrinkage and pleural change are present in a high proportion of patients and are frequently identified in RILD. GGOs, reticulation and traction bronchiectasis are common at 12 months but not diagnostic.

Consecutive CT-guided core needle tissue biopsy of lung lesions in the same dog at different phases of radiation-induced lung injury

This project aimed to set up a Beagle dog model of radiation-induced lung injury in order to supply fresh lung tissue samples in the different injury phases for gene and protein research. Three dogs received 18 Gy X-ray irradiation in one fraction, another three dogs received 8 Gy in each of three fractions at weekly intervals, and one control dog was not irradiated. Acute pneumonitis was observed during the first 3 months after radiation, and chronic lung fibrosis was found during the next 4-12 months in all the dogs exposed to radiation. CT-guided core needle lung lesion biopsies were extracted from each dog five times over the course of 1 year. The dogs remained healthy after each biopsy, and 50-100 mg fresh lung lesion tissues were collected in each operation. The incidence of pneumothorax and hemoptysis was 20% and 2.8%, respectively, in the 35 tissue biopsies. A successful and stable radiation-induced lung injury dog model was established. Lung lesion tissue samples from dogs in acute stage, recovery stage and fibrosis stage were found to be sufficient to support cytology, genomics and proteomics research. This model safely supplied fresh tissue samples that would allow future researchers to more easily explore and develop treatments for radiation-induced lung injury.

Plasma ceramide, a real-time predictive marker of pulmonary and hepatic metastases response to stereotactic body radiation therapy combined with irinotecan

BACKGROUND AND PURPOSES

Early biomarkers of tumour response are needed to discriminate between responders and non-responders to radiotherapy. We evaluated the ability of ceramide, a bioactive sphingolipid, to predict tumour sensitivity in patients treated by hypofractionated stereotactic body radiation therapy (SBRT) combined with irinotecan chemotherapy.

MATERIALS AND METHODS

Plasma levels of total ceramide and of its subspecies were measured before and during treatment in 35 patients with liver and lung oligometastases of colorectal cancer included in a phase II trial. Cer levels were quantified by LC-ESI-MS/MS and compared to tumour volume response evaluated one year later by CT-scan.

RESULTS

Pretreatment plasma ceramide levels were not indicative of tumour response. Nevertheless, the levels of total ceramide and of its 4 main subspecies were significantly higher at days 3 and 10 of treatment in objective responders than in non-responders. According to Kaplan-Meier curves, almost complete tumour control was achieved at 1year in patients with increased total ceramide levels whereas 50% of patients with decreased levels experienced an increase in tumour volume.

CONCLUSIONS

Total plasma ceramide is a promising biomarker of tumour response to SBRT combined with irinotecan that should enable to segregate patients with high risk of tumour escape.

[Positron emission tomography and stereotactic body radiation therapy for lung cancer: From treatment planning to response evaluation]

Stereotactic body radiation therapy is the standard treatment for inoperable patients with early-stage lung cancer. Local control rates range from 80 to 90 % 2 years after treatment. The role of positron emission tomography in patient selection is well known, but its use for target definition or therapeutic response evaluation is less clear. We reviewed the literature in order to assess the current state of knowledge in this area.

Classification and Reporting of Late Radiographic Changes After Lung Stereotactic Body Radiotherapy: Proposing a New System

Radiation-induced parenchymal lung changes after stereotactic body radiotherapy are common, and can obscure the primary tumor site. In this study we propose a structured radiographic reporting tool for characterization of these changes, pilot its feasibility in a group of radiation oncologists, and test the interrater agreement. We could demonstrate the applicability of the scale, with a fair to moderate agreement.

BACKGROUND

The purpose of the study was to design and pilot a synoptic scale for characterization of late radiographic changes after lung stereotactic body radiotherapy (SBRT).

PATIENTS AND METHODS

A participatory design process involving 6 radiation oncologists and 2 thoracic radiologists was used in the scale's design. Seventy-seven early-stage non-small-cell lung cancer patients who were treated with SBRT were included, and after treatment their serial computed tomography (CT) images were scored by 6 radiation oncologists. Gwet's First-order Agreement Coefficient (AC1) and a leave-one-out (LOO) analysis was used to assess interrater reliability and variability among raters, respectively.

RESULTS

The scale reports on 5 independent categories including "tumor in primary site," "tumor in involved lobe," "consolidation," "volume loss," and "ground-glass or interstitial changes." At each time point, each category is reported as "increased," "stable," "decreased," "obscured," or "not present," compared with the previous. The total number of rated images for the pilot ranged from 450 at 6 months to 84 at 48 months. The primary tumor site was scored as obscured in 38% to 40% of ratings from 12 months onward; 3% to 5% of primary tumors were scored as "increased." Consolidation, volume loss, and ground-glass or interstitial changes were increasingly marked as "stable" with time. At 24 months, AC1 was 0.28 (LOO, 0.22-0.42), 0.47 (LOO, 0.39-0.72), 0.45 (LOO, 0.42-0.50), 0.21 (LOO, 0.15-0.26), and 0.25 (LOO, 0.20-0.38) for the 5 categories listed, respectively.

CONCLUSION

In a population of clinicians, this scale could be implemented to characterize evolving lung changes after SBRT, and had fair to moderate interrater agreement. Obscured tumor site is a common challenge of follow-up CT imaging, and new imaging techniques should be explored. This scale provides a tool for communicating changes after SBRT.

Extracranial stereotactic body radiotherapy. Review of main SBRT features and indications in primary tumors

AIM

Review of main SBRT features and indications in primary tumors.

BACKGROUND

Stereotactic body radiotherapy has been developed in the last few years. SBRT allows the hypofractionated treatment of extra cranial tumors, using either a single or limited number of dose fractions, and resulting in the delivery of a high biological effective dose with low toxicity.

MATERIAL AND METHODS

SBRT REQUIRES A HIGH LEVEL OF ACCURACY FOR ALL PHASES OF THE TREATMENT PROCESS: effective patient immobilization, precise target localization, highly conformed dosimetry and image guided systems for treatment verification. The implementation of SBRT in routine requires a careful considering of organ motion. Gating and tracking are effective ways to do so, and less invasive technologies "fiducials free" have been developed. Due to the hypofractionated scheme, the physician must pay attention to new dosimetric constraints in organ at risk and new radiobiological models are needed to assess the optimal fractionation and dose schemes.

RESULTS

Currently, SBRT is safe and effective to treat primary tumors, which are otherwise untreatable with conventional radiotherapy or surgery. SBRT has quickly developed because of its excellent results in terms of tolerance and its high locoregional control rates. SBRT indications in primary tumors, such as lung primary tumors, have become a standard of care for inoperable patients. SBRT seems to be effective in many others indications in curative or palliative intent such as liver primary tumors, and novel indications and strategies are currently emerging in prostate cancer, head and neck tumor recurrences or pelvis reirradiations.

CONCLUSION

Currently, SBRT is mainly used when there is no other therapeutic alternative for the patient. This is due to the lack of randomized trials in these settings. However, the results shown in retrospective studies let us hope to impose SBRT as a new standard of care for many patients in the next few years.